Matrix generation based on list's objects in R-CodePudding

I have a list of objects in R like follows:

set.seed(1234)
data <- matrix(rnorm(3*4,mean=0,sd=1), 3, 4) 
results <- lapply(1:ncol(data), function(i) outer(data[, i], data[, i]))

which will result in the following matrices

[[1]]
           [,1]        [,2]       [,3]
[1,]  1.4570077 -0.33487534 -1.3089918
[2,] -0.3348753  0.07696698  0.3008557
[3,] -1.3089918  0.30085569  1.1760127

[[2]]
          [,1]       [,2]       [,3]
[1,]  5.502298 -1.0065968 -1.1870541
[2,] -1.006597  0.1841480  0.2171611
[3,] -1.187054  0.2171611  0.2560926

[[3]]
          [,1]      [,2]      [,3]
[1,] 0.3303260 0.3141712 0.3244131
[2,] 0.3141712 0.2988064 0.3085474
[3,] 0.3244131 0.3085474 0.3186061

[[4]]
          [,1]      [,2]      [,3]
[1,] 0.7921673 0.4247196 0.8886017
[2,] 0.4247196 0.2277129 0.4764227
[3,] 0.8886017 0.4764227 0.9967755

How can I create a single matrix containing the Interquartile Range (IQR) between the corresponding elements? Meaning the new matrix will be a B=3X3 matrix with for example B(1,1)=IQR(c(1.4570077,5.502298,0.3303260,0.7921673))=1.791623, B(1,2)=IQR(c(-0.33487534, -1.0065968, 0.3141712, 0.4247196))= 0.844614. How can I use the apply function to create this new matrix?

CodePudding user response：

We may convert the list to array and then use apply with MARGIN as c(1, 2) and apply the IQR elementwise

apply(simplify2array(results), c(1, 2), IQR)

-output

      [,1]       [,2]       [,3]
[1,] 1.791623 0.84461397 1.68299882
[2,] 0.844614 0.08813351 0.07058422
[3,] 1.682999 0.07058422 0.73860710

Or another option is transpose the list and then apply the IQR by looping over the list

library(purrr)
`dim<-`(map_dbl(transpose(results), IQR), dim(results[[1]]))
         [,1]       [,2]       [,3]
[1,] 1.791623 0.84461397 1.68299882
[2,] 0.844614 0.08813351 0.07058422
[3,] 1.682999 0.07058422 0.73860710